Fan and impeller thereof

ABSTRACT

A fan has an impeller, a motor and a frame. The impeller and the motor are disposed within the frame, and the motor is connected to the impeller and drives the impeller to rotate. The impeller includes a hub and an odd number of blade sets. The blade sets are disposed around the circumference of the hub. Bach blade set has a plurality of the blades, and the blades of each blade set can be the same or not. For example, the blades in each of the blade sets have different tilting angles, heights and/or lengths while the blades are connected with the hub. Or the blades in each of the blade sets have different curvatures, arc lengths, thicknesses, or side-view shapes.

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 096112018, filed in Taiwan, Republic of China on Apr. 4, 2007, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to a fan and an impeller thereof, and in particular to a fan and an impeller thereof with an odd number of blade sets.

2. Related Art

As developments of electronic products with good performance, high operating frequencies, fast speeds and compact sizes, lots of heat and thus high temperature are generated that easily results in instability during their operations and affects the reliabilities of the electronic products. Therefore, heat dissipation has become one important issue in the design of electronic devices.

Fan is a commonly used in heat dissipation. FIG, 1 shows a conventional fan 1. The impeller 10 and the motor 11 are disposed within the frame 13, and the motor 11 is disposed inside of the hub 102 to drive the impeller 10 to rotate.

In the design of the fan 1, the number of blades 101 is always selected to be odd. The reason is to avoid its resonance with other components, such as the coil set 111 of the motor 11 or the ribs 131 on the frame 13 when the fan 1 rotates. Such resonances increase the noises, cause imbalance, and result in fatigue of the bearing and other elements, thereby affecting the overall performance of the fan and lowering its lifetime.

However, due to higher demands in heat dissipation, the performance of the fan I has to increase as well. To increase the air flow and air pressure, a common method is to enlarge the width of the blades 101. Nevertheless, there is a limit in the angle between adjacent blades, which will put a restriction on the blade width. Alternatively, increasing the number of blades 101 to enhance the air flow and air pressure will produce phenomena of resonance among the components.

SUMMARY OF THE INVENTION

In view of the foregoing, the present invention is to provide a fan and an impeller thereof that can increase the air flow and air pressure without producing resonance effects or sacrificing their lifetime.

To achieve the above, the present invention discloses an impeller including a hub and an odd number of blade sets. The blade sets are disposed around the circumference of the hub, and each of the blade sets includes a plurality of blades.

To achieve the above, the present invention also discloses a fan including an impeller, a motor and a frame. The impeller and the motor are disposed in the frame. The impeller includes a hub and an odd number of blade sets disposed around the circumference of the hub. Each of the blade sets includes a plurality of blades. The motor is connected to the impeller for driving the impeller to rotate.

As mentioned above, the fan and impeller of the present invention have the design that several blades are grouped into an odd number of blade sets. Therefore, at the same time of increasing the overall air flow and air pressure of the fan by having more blades, the system is still kept balanced. Compared with the prior art, the present invention is free from the design restriction of having an odd number of blades. It also prevents the resonance phenomena when there are the total blades of even number. Thus, the efficiency of the fan is increased. Moreover, the blades in each blade set can be the same or different, thereby increasing the flexibility in blade designs.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and accompanying drawings, which are given for illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a schematic view of a conventional fan;

FIGS. 2A and 2B are the front and back views of a fan according to the preferred embodiment of the present invention;

FIG. 2C shows the impeller in FIG. 2A;

FIGS. 3 to 5 are schematic views showing various kinds of impellers according to the embodiment of the present invention;

FIG. 6 shows an expansion of the cross section of the blades with different tilting angles according to the embodiment of the present invention;

FIG. 7 shows an expansion of the cross section of the blades with different heights according to the embodiment of the present invention;

FIG. 8 shows an expansion of the cross section of the blades with different curvatures and thicknesses according to the embodiment of the present invention;

FIG. 9 shows an expansion of the cross section of the blades with different arc lengths according to the embodiment of the present invention; and

FIG. 10 is a schematic view of another impeller according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.

FIGS. 2A and 2B are the front and back views of a fan 2 according to an embodiment of the present invention. Referring to FIGS. 2A and 2B, the fan 2 includes an impeller 20, a motor 21 and a frame 23. The impeller 20 and the motor 21 are disposed within the frame 23. The motor 21 is connected with the impeller 20 to drive it to rotate. In this embodiment the fan 2 is, for example but not limited to, an axial-flow fan. Of course, the fan of the present invention can be a centrifugal fan as well.

FIG. 2C shows the impeller 20 in FIG. 2A. With reference to FIGS. 2A and 2C, the impeller 20 includes a hub 21 and an odd number of blade sets 22. The blade sets 22 are disposed around the circumference of the hub 21. Each blade set 22 has at least two blades 221. In this embodiment, the circumference of the hub 21 is provided with five blade sets 22 including the groups G1, G2, G3, G4 and G5, The blade sets 22 are disposed at equal interval around the circumference of the hub 21. As shown in FIG. 2, five blade sets 22 are disposed around the circumference of the hub 21, and each blade set 22 has two blades 221. Thus, in this case, the fan 2 has ten blades 221. Since the blades 221 on the impeller 20 are divided into an odd number of blade sets 22, the chance of producing resonance with other components of the fan 2 during the operation of the impeller 20 is reduced. Moreover, because each blade set has several blades, the total contact area of the fan is increased to enhance the wind flux.

However, the present invention is not limited to the above-mentioned example. For example, there can be nine blades grouped into three blade sets with three blades each, or twelve blades grouped into three blade sets with four blades each. Therefore, the present invention only specifies an odd number of blade sets and each blade set has a plurality of blades.

In this embodiment, the blades 221 in one blade set 22 are different from each other. As shown in FIG. 2C, the blades 221 a and 221 b in one blade set 22 have different shapes and curvatures. Alternatively, as shown in FIG. 3, the blades 321 a and 321 b in one blade set 32 of the impeller 30 have different lengths. Of course, the present invention is not limited to these examples. In FIG. 4, for example, the blades 421 a and 421 b in one blade set 42 of the impeller 40 are the same.

According to needs, the adjacent blades 521 a and 521 b in one blade set 52 of the impeller 50 can partially overlap with each other, as shown in FIG. 5. The fan with the impeller 50 can be used in electronic devices with a light source, such as projectors. Since the adjacent blades 521 a and 521 b are partially overlapped in the radial projection, it can effectively block the light emitted from the light source.

FIG. 6 shows an expansion of the cross section of the blades with different tilting angles according to the embodiment of the present invention. In FIG. 6, the tilting angle Θ1 of the blade 621 a in one blade set 62 is different from the tilting angle Θ2 of the blade 621 b. The blades 621 a of the same tilting angle Θ1 in different blade sets 62 are located corresponding to one another, and the blades 621 b of the same tilting angle Θ2 in different blade sets 62 are also located corresponding to one another. In other words, the blades 621 a of the same tilting angle Θ1 and the blades 621 b of the same tilting angle Θ2 are disposed alternately on the hub 61.

In addition to different tilting angles for the blades in each blade set, the heights of the blades connecting to the hub can be different as well. That is, the blades are disposed on different planes of the hub. As shown in FIG. 7, in each blade set 72, the height L1 of the blade 721 a connecting to the hub 71 is different from the height L2 of the blade 721 b connecting to the hub 71.

Furthermore, the blades in each blade set can have different curvatures or thicknesses. As shown in FIG. 8, the blades 821 a and 821 b in one blade set 82 have thicknesses T1 and T2, respectively, where T1 is not equal to T2. In addition, the blades of each blade set can have different arc lengths. As shown in FIG. 9, the blades 921 a and 921 b in each blade set 92 have arc lengths S1 and S2, respectively, where S1 is not equal to S2. Moreover, the side views of the blades can be different. When each blade set has more than two blades, the intervals between them can be different too.

Please refer to FIG. 10. Another impeller 26 according to the embodiment of the present invention has similar compositions and features to the impeller 2 in FIG. 2C. The difference is in that the impeller 26 in FIG. 10 further includes at least one reinforcing element 27 and each blade 221 is connected to the reinforcing element 27. More explicitly, the reinforcing element 27 is ring-shaped and is disposed along the circumference of the blades 221, so that the end of each blade 221 is connected to the reinforcing element 27. This configuration strengthens the structural strength of the impeller 26, thereby improving the problem of deformation at the ends of the blades under high-speed rotations if the blades 221 are too long. Moreover, the reinforcing element 27 evenly distributes the force on each blade 221 so as to stabilize the rotating impeller 26.

In summary, the fan and impeller of the present invention have the design that several blades are grouped into an odd number of blade sets. Therefore, at the same time of increasing the overall air flow and air pressure of the fan by having more blades, the system is still kept balanced. Compared with the prior art, the present invention is free from the design restriction of having an odd number of blades. It also prevents the resonance phenomena when there are the total blades of even number. Thus, the efficiency of the fan is increased. Moreover, the blades in each blade set can be the same or different, thereby increasing the flexibility in blade designs,

Although the present invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the present invention. 

1. An impeller, comprising: a hub; and an odd number of blade sets disposed around a circumference of the hub, wherein each of the blade sets comprises a plurality of blades.
 2. The impeller of claim 1, wherein all blades in each of the blade sets are the same.
 3. The impeller of claim 1, wherein the blades in each of the blade sets are different.
 4. The impeller of claim 3, wherein the blades in each of the blade sets have different tilting angles, heights and/or lengths while the blades are connected with the hub.
 5. The impeller of claim 3, wherein the blades in each of the blade sets have different intervals between two adjacent blades.
 6. The impeller of claim 3, wherein the blades in each of the blade sets have different curvatures, arc lengths, thicknesses, or side-view shapes.
 7. The impeller of claim 3, wherein numbers of the blades in each of the blade sets are the same.
 8. The impeller of claim 7, wherein the blades in each of the blade sets are disposed corresponding to the blades in another blade set.
 9. The impeller of claim 1, wherein the blade sets are disposed around the circumference of the hub with equal intervals.
 10. The impeller of claim 1, wherein adjacent blades in each of the blade sets are partially overlapped with each other.
 11. The impeller of claim 1, further comprising at least one reinforcing element connected to all of the blade sets, wherein the reinforcing element is ring-shaped.
 12. A fan comprising: an impeller, comprising a hub and an odd number of blade sets disposed around a circumference of the hub, wherein each of the blade sets comprises a plurality of blades; a motor connected to the impeller and driving the impeller to rotate; and a frame, wherein the impeller and the motor are disposed in the frame.
 13. The fan of claim 12, wherein all blades in each of the blade sets are the same.
 14. The fan of claim 12, wherein the blades in each of the blade sets are different.
 15. The fan of claim 14, wherein the blades in each of the blade sets have different tilting angles, heights and/or lengths while the blades are connected with the hub.
 16. The fan of claim 14, wherein the blades in each of the blade sets have different intervals between two adjacent blades.
 17. The fan of claim 14, wherein the blades in each of the blade sets have different curvatures, arc lengths, thicknesses, or side-view shapes.
 18. The fan of claim 14, wherein numbers of the blades in each of the blade sets are the same, and the blades in each of the blade sets are disposed corresponding to the blades in another blade set.
 19. The fan of claim 12, wherein adjacent blades in each of the blade sets are partially overlapped with each other.
 20. The fan of claim 12, wherein the impeller further comprises at least one reinforcing element connected to all of the blade sets, and the reinforcing element is ring-shaped. 